This invention relates to an apparatus for delimbing top portions of standing trees, primarily coniferous, where such apparatus is suspended above a tree to be partially delimbed, by a helicopter, crane or similar equipment and lowered so that the uppermost branches are sawn off close to the trunk of the tree.
It is often desirable to harvest a single tree amongst a stand of trees, without having to fall and delimb the tree once fallen. For example, single trees may be culled by helicopter harvesting techniques which do not disturb the surrounding trees. This requires delimbing of the tree while it stands.
Another example of the utility of the present invention involves standing trees left adjacent to the periphery of logged off areas or at the perimeter of riparian zones or leave-strips. Such trees are subject to wind turbulence and snow loading, which results in many trees falling over or becoming hazardous, so-called snags.
By reducing the catchment area of individual trees, that is the branch area near the crown which catches wind or snow, the effect of wind and snow loading on the exposed trees may be reduced. This, in turn, reduces the adverse effect such forces have on the stability of these trees. The reduction in tree catchment area can be accomplished by hand delimbing but this is neither time nor cost effective.
It is an object of the present invention to provide a delimbing apparatus containing a rotatable annular saw, which may be suspended, from a helicopter, crane or other like lifting devices, so as to be positioned over the crown of a tree, and lowered in a controlled manner to efficiently delimb the upper portion of the tree.
In the prior art applicant is aware of U.S. Pat. No. 6,263,932 which issued Jul. 24, 2001, for the Aerial Tree Harvesting Apparatus of Chalifoux. Chalifoux discloses the use of tree delimbing saws in a second body suspended from a first body, the first and second bodies having coaxial bores for mounting over a tree. The tree is delimbed as the second body is lowered over the tree. Arms are provided for clamping and holding the tree.
The aerial tree delimbing apparatus of the present invention has in one embodiment a tubular body having an upwardly and radially outwardly flared collar at an upper first end and branch engaging rods projecting downwardly from an opposite second end. The delimbing apparatus is suspended by suspension cables connected at one end of the cables to the swivel of a sling or lanyard, or other suitable equipment for slinging under a helicopter for example. The other ends of the cables are connected to the flared collar of the body of the delimber. The swivel is advantageously of the type which will conduct an electrical current or allow or provide for conduction of electricity from the helicopter to the delimber, although other means for supplying power may be provided. The suspension cables may be spaced apart by a spreader disk for example located in general proximity to the swivel.
A saw drive sprocket surrounds the tubular body near the second end of the body. It is rotatably mounted to the body by an annular bearing having an inner and an outer bearing race. The inner bearing race is fixedly secured to the tubular body of the delimber, while the outer race and the annular sprocket is freely rotatable therearound. An annular saw is secured to the outer bearing race so as to be cooperatively rotatable with both the outer bearing and the sprocket. The sprocket and annular saw are simultaneously rotated by a motor mounted to the tubular body of the delimber. The motor selectively drives a sprocket and chain. Rotation of the sprocket and chain drives the annular saw through a centrifugal clutch. The throttle of the motor is operated by an electric solenoid, which is remotely actuable by the operator of the helicopter or other lifting equipment.
In operation the solenoid is actuated so as to start the motor. The clutch engages so as to commence the saw rotating. Saw rotation increases to an operational speed. The delimber is suspended over the crown of a tree. As the delimber is lowered, the outwardly projecting branch engaging rods engage tree branches in the crown maintaining the delimber stationary relative to the tree while the annular saw cuts through the branches.
Since the diameter of the annular saw is less than the diameter of the outermost perimeter of the flared collar at the first end of the tubular body, the collar acts as a funnel so that delimber may be easily lifted upwardly and removed from the tree without catching on the remaining stubs of the sawn branches.
In summary, the tree delimber of the present invention includes a hollow tube having opposite upper and lower ends. The upper end is adapted for mounting below an aerial hoist, for example at the end of a helicopter borne sling. The lower end has an anti-rotation means or device such as a branch coupler mounted thereto, for example, a plurality of downwardly extending rigid members. The anti-rotation means is for coupling with, mating into or temporarily entangling with the branches of a tree as the trunk of the tree is journalled through the hollow tube as the tube is lowered onto the tree and down the trunk. The anti-rotation means inhibits rotation of the tube about the axis of symmetry of the tube, which is generally co-axial with the trunk of the tree.
A collar is rotatably mounted to the lower end of the tube. An annular saw blade is mounted to the collar so as to dispose a cutting edge or saw blade teeth of the saw downwardly. The cutting edge or teeth of the saw rotate in a circle contained in a plane generally perpendicular to the axis of symmetry of the tube.
A prime mover is mounted to the tube. The prime mover is remotely actuable by an operator. The prime mover cooperates with the collar so that, once actuated, the prime mover urges the collar to rotate about the axis of symmetry of the tube while the tube is held substantially stationary relative to the trunk by the anti-rotation device engaging the tree branches.
An upwardly diverging funnel may be rigidly mounted to the upper end of the tube.